Do you have a previous version of Office on your system? You may need to completely uninstall it first, reboot the machine, and try the installation again, especially if you had/have Office 2003 on it.

Otherwise, look in your Temp folders for files named similar to Microsoft Office Setup(####).txt where the #### is a 4 digit number starting at 0001. Zip them up and post them somewhere that we can pick them up to see what is going on during your installation.

are you installing from dvd? or you have the setup?
1) copy the full setup (or copy the files from dvd) to the root of your hard drive containing windows like C:
2) open command prompt with admininstrative rights and type cd/
3) Now enter the setup name of the office and hit enter
see if install will be completed this time